1) Field of the Invention
The present invention relates generally to brackets for use with agricultural toolbars and tool mounting tubes, and, more specifically, to adjustable bracket structure for firmly mounting a rig or other attachment on toolbars or tubes having different cross sections.
2) Related Art
In a variety of agricultural implements, U-bolts or equivalent bolt structures secure a flanged mounting bracket to one face of a toolbar or other mounting tube having a rectangular or square cross section. Depending on the implement and application, the cross section of the tube varies and requires either an adjustable bracket and bolt structure or a completely different mounting structure to accommodate an increase or decrease in the dimension of the face to which the flanged bracket is secured. Adjustable brackets or open slotted brackets can be used with different U-bolts or bolt structure, but such brackets often can be expensive and cumbersome to mount. Some slotted or otherwise adjustable structures provide less than optimum gripping around all sides of the tube, particularly in heavy loading situations that are encountered by the implements. Often the adjustable structures do not positively position the threaded legs of a U-bolt or the other bolt structure. Conical washers or inserts adapted for entry into the mounting holes of the bracket have been provided to increase the grip by the bracket on the sides of the tube, but such inserts do not provide sufficient adjustability to accommodate tubes of differing cross section and can cause excess bending forces and unpredictable clamping forces near the ends of the bolt structure.